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Tuesday, May 27, 2014

In cold and temperate water habitats, starfish, especially asteriid starfish are often predatory. ESPECIALLY on mollusks! Famously on bivalves and clams but also quite a few gastropods aka snails.

But in the tropics, we often find the tables are turned! Snails, especialy giant snails, such as these Giant Tritons (Charonia sp.) are big, ol' meanie predators on several often, equally large and heavily armored (or at least well-defended) starfish species...

The Triton Vs. Crown of Thorns (Acanthaster planci)
Just walked out of Godzilla and want to see two big monsters fight it out?? You've come to the right place!

The "Triton's Trumpet" is a large snail with a shell that is often up to two feet long. Because it is large and showy, it is often sought after as a souvenir. Here we have not one but TWO videos of these giant snails attacking the very spiny Crown of Thorns starfish, a voraceous predator of corals

When the snails get to work, they often appear to be successful. But even if not, with the crown-of-thorns starfish there's *literally* many more fish (or starfish) in the sea!

this did not end well for the starfish.

The Triton vs. the "Blue Linckia" aka Linckia laevigata
Here..what you are seeing is NOT a hermit crab, but one of these giant triton snails finishing off its dinner, a blue Linckia laevigata, eating it disk first with the legs sticking out of the shell's opening..

The truth is that they live frakkin' EVERYWHERE. The diversification of brittle stars is thought to have been successful mainly because they've found a niche just about anywhere and everywhere they can! They live in all the nooks and crannies on the marine bottoms: buried in sediment, rocks, sponges, corals so on and so forth..

3. Hydrothermal Vents.
Here is ANOTHER place you generally don't expect to find echinoderms. Why? Because most of the environment around hydrothermal vents is not just, very, VERY hot but also filled with toxic chemicals, such as hydrogen sulfide.

Given how sensitive most echinoderms are to having clean, seawater these factors probably exclude most other echinos from being present in these poisonous areas. and YET somehow brittle stars have found a living here.

Observe Ophiolamina eprae from the East Pacific Rise. And there are actually about three others that live in and around vent settings...

This species actually looks like it lives directly in the path of some of the hot water and toxic materials...

Echinoderms are exclusively marine and they don't handle shifts in the amount of salinity in the water well. Some echinoderms, such as sea stars will often die from a significant drop in ocean salinity from say, a big rainstorm.

Salinity in ocean water ranges about 30-50 ‰ (ppt) and freshwater is generally less than 0.5 ‰ (ppt). A lot of sea stars, for example start to get unhappy when you drop below 30ish ‰ (ppt).

But some brittle stars? Brittle stars are probably the toughest of the echinoderms with some species, such as the above Ophiophragmus filograneus (Amphiuridae) can withstand up to 7.7 ‰ (or ppt-parts per thousand).Another species in the Amphiuridae, Amphipholis squamata has been recorded as withstanding salinity as low as 5 ‰ !!

In the salinity battle, brittle stars are tough, little bastards.5. Crinoids!
Here's one species, Ophiomaza chaotica a strikingly black and white specieswhich famously lives on feather stars! A short write up on it at Wild Singapore here.

BONUS!
and I found this pic of a tiny striped brittle star living on Ophiomastix annulosa Another example of commensalism?? Maybe one just incidentally crawling on the other? It wasn't actually clear and unfortunatley I couldn't actually find a record Ophiomastix-on-Ophiomastix action..so for now a mystery...

There ARE some accounts of brittle stars living symbiotically on other brittle stars but for various reasons, those are the subject of a future post!

UPDATE: Should also have mentioned that brittle stars live on that other extreme deep-sea habitat-WOOD. But that's a story for another day...

So, the paper's primary focus was on the family Poraniidae, which is a small but unusual group of cold-water starfishes which have kind this weird fleshy covering over their skeleton.

The surface of these animal is soft to the touch and they look sort of velvety like so.... (Porania pulvillus is shown).

Truthfully, no one has known much about them and as such, it was unclear what kind of relevance they had to the bigger scheme of biology.

A few years ago, starfish paleontologist Dan Blake described Noriaster barberoi from the Triassic of Italy. Triassic starfish fossils are incredibly rare and potentially provide insight into the early evolution and history of all starfishes.

Dr. Blake identified these fossil starfish as members of the Poraniidae, making them potentially important in the "big tree" of starfish evolution.

But we understood very little about the ecology and life modes of LIVING members of this group.

But usually, one of the first steps towards understanding these "family trees" is to "straighten out" the many different kinds of genera and species in the Poraniidae. (or any discrete group of starfishes).

There's a LOT of stuff in a paper like this..so here are some highlights...

There's an overview of known genera and speciesChondraster grandis? from the North Atlantic. We know almost nothing about this species..

Here is Poraniopsis inflata, which occurs along the Pacific coast from Japan to Alaska and south along the west coast of North America to California. A related species occurs widely in the Southern Hemisphere.

Some new genera and species...

One of the delights in looking through big museum collections and specimens from an endless number of research expeditions is the possibility of finding a new species or even a new genus!

In the bigger, evolutionary sense, this would be like finding a long lost member of your family you never knew about. Then, you need to figure out how/where/who it is...

First..may I present the new genus and species: Clavaporania fitchorum!

The new genus is named "Clava" or club shaped which refers to the spine and "Porania" which is the name from which the family Poraniidae derives its name. The species is named for Mason & Lisa Fitch, who are ardent supporters of my research!

The OTHER new, cool species we found was a tiny little (it was about 1.5 inches across) animal collected by the Monterey Bay Aquarium Research Institute (MBARI) from Davidson Seamount in the North Pacific from an astonishing 2669 meters! I have much thanks to benthic ecologist Jim Barry and biologist Lonny Lundsten for their help in making the animal available to me.

with new species, come NEW observations! MBARI was working on/collecting this deep-sea "black coral" aka an antipatharian..

The new species (note the white arrow) was found among the other echinoderms present on the branches

My take on the pictures was that this starfish was feeding on the fronds since to my eye, some of those fronds are gone..So, PREDATION???

I couldn't help notice that the animal had actually crawled UP into the branches. And from that I gave the animal its species name- Bathyporania ascendens. The genus was Bathyporania which comes from "Bathy" for depth and "Porania" which again is a the primary name for taxa in the Poraniidae. species is called "ascendens" for "ascent" or to climb because of the fact that it climbed up into the branches of this black coral...

And the case I made there was simply this: Poraniids had always been thought of as fairly passive feeders. What if they AREN'T?? Maybe they feed more aggressively as predators?? And this line of thinking from the blog eventually made its way into a nice part of the paper discussion! which for me, leads to a nice paradigm shift about this poorly known group of animals!
The internet observations had colored and further fleshed out my published work! Who knows how it will be corrupted by blogging next? Woo!

Crinoid feeding biology is fundamentally a simple matter. Arms are outstretched into the water current and food is caught by the branching on the arms and moved to the mouth present in the cup (also called the calyx which is a damn good Scrabble word).

Of the approximately 600 species of crinoids alive today, about 95 of them are stalked but belong to a diversity of different genera, family and species. Nearly all of these live in the deep-sea where they occur at great depth, ranging down to the deepest known depths (9000 meters!)

One of the primary differences in overall morphology is how and whether they are attached.. As you can see, the yellow Hyocrinus (family Hyocrinidae) on the left side is permanently anchored to the rock, whereas the Endoxocrinus (Isocrinidae) on the right side has a stalk that ends as kind of a tail, which allows it to crawl around and move. (presumably to escape predators as outlined here).

Like their shallow water counterparts, its not unusual to find several stalked crinoids in the same place, taking advantage of a good water current for feeding... which makes for an almost surreal deep-sea bottom...

About Me

I pursue starfish related adventure around the world with a critical eye and an appreciation for weirdness.
Support has been courtesy of the National Science Foundation but the views and opinions presented herein are mine and do not reflect the opinions of them or any affiliated institutions.
Need to hire an invertebrate zoologist/marine biologist? Please contact me!